Circuit breaker trip mechanism



NOV. 4, 1958 PLATZ ETAL' 2,859,300

CIRCUIT BREAKER TRIP MECHANISM Filed Nov. 24, 1953 2 Sheets-Sheet 1 NOV. 4, 1958 PLATZ ETAL 2,859,300

' CIRCUIT BREAKER TRIP MECHANISM Filed NOV. 24, 1953 2 Sheets-Sheet 2 INVENTORS. fizz 404 7 F 422 /7g&rz 14 farr/ds United States Patent CIRCUIT BREAKER TRIP MECHANISM Elwood T. Platz, Detroit, and Robert W. Thomas, St. Clair Shores, Mich., assignors, by mesne assignments, to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application November 24, 1953, Serial No. 393,987 13 Claims. (Cl. 20095) This invention relates to electric circuit breakers, generally and specifically to an improvement in overload tripping mechanism used in such circuit breakers. 'It is adapted particularly to the type of circuit breaker shown in prior pending application Serial No. 342,174, filed March 13, 1953, and assigned to the assignee of the present application.

A principal object of the invention is to provide a variable overload trip mechanism in a circuit breaker.

' cuit breaker with the side wall cut away to show 'theinvention disengaged from the circuit breaker trip mechanism.

Fig. 2 is a side elevational view of a portion of a circuit breaker with the side wall cut away to show an embodiment of the invention engaged with the circuit breaker trip mechanism.

Fig. 3 is a side elevational view of a portion of a circuit breaker with the side wall cut away to show the operation of an embodiment of the invention.

Fig. 4 is a partial cross-sectional view as if on line 44 of Fig. 5.

Fig. 5 is a side elevational view of a portion of a circuit breaker with the side wall cut away showing another embodiment of the invention in alternative positions of engagement and disengagement with the circuit breaker trip mechanism.

Referring to the drawings, Fig. 1 shows a portion of a circuit breaker of the type disclosed in co-pending application Serial No. 342,174, referred to hereinabove. The particular circuit breaker embodiment shown therein is known in the art as a three pole circuit breaker and functions to interrupt the flow of electric current in the three circuits connected thereto upon the occurrence of an overload in one or more of the circuits. Furthermore, the circuit breaker is trip free, which means it can function to interrupt the flow of electric current independent of the position of the manual operator. As disclosed in that application, such a circuit breaker denoted herein generally as 11 includes a housing 13 of suitable insulating material, a control mechanism indicated generally as 12 for controlling interruption of electric current flowing through the breaker, and an automatic tripping mechanism 14. This automatic tripping mechanism 14 includes a frame 15, a magnetic trip coil unit 16 for each pole (only one of which is shown), and an armature 17 disposed above each magnetic trip coil unit. A

2,859,300 Patented Nov. 4, 1958 common trip bar 19 extends across all poles of the circuit breaker to initiate actuation of the breaker mechanism 12 as hereinafter described. A return spring 52 biases common trip bar 19 counterclockwise about pivot 20 to restore it to a nonoperative position. Secured to the upper part of each armature 17 and overlying the upper surface of common trip bar 19 is a trip bar actuator 18. Upon the occurrence of an overload in any of the circuits connected to the breaker, the armature 17 associated with the magnetic trip coil unit in that particular circuit is attracted to magnetic trip coil unit 16. Through trip bar actuator 18, the common trip bar 19 is pulled downwardly about pivot 20 to initiate operation of the breaker control mechanism 12 to the Otf circuit position.

Disposed in the. cover 21 of housing 13 as shown in Figs. 1, 2, 3, 4 is a unitary lock 51 of the tumbler type. This lock is comprised of a mounting base 22, a casing 23, and a lock mechanism 24 which is rotatable within casing 23 by a key 25. A lock nut 26 engages threads upon casing 23 to positively secure the lock in cover 21. In the preferred embodiment of the invention shown in Figs. 1, 2, 3 a metal bracket 28 is positively secured to the lock mechanism 24 by screws 27. Bracket 28 has downwardly turned extensions 29 at one end for supporting pivot pin 30. The opposite end of bracket 28 has an opening 31 and a downwardly turned lip 32. Disposed in opening 31 of bracket 28 with a threaded portion extending below bracket 28 is an adjusting member 33 having a notched head 34. A calibrating spring 40 is confined between head 34 and the upper surface of bracket 28. Disposed below bracket 28 with one end secured between extensions 29 to pivot pin 30 is a control bar 35. This control bar 35 has a portion 36 bent down at a right angle. This bent-down portion 36 has a portion cut away to form a trip bar notch 37 the lower edge of which is rounded as shown in Fig. 2 and 3. This formation facilitates engagement of this member with the common trip bar 19 as hereinafter described. Adjacent to the end of the body of control bar 35 is a tapped opening 38 which receives the threaded portion of adjusting member 33. The force of calibrating spring 40, which is in compression, biases control bar 35 upwardly against the lower edge of downwardly turned lip 32 of bracket 28 as shown in Fig. 1.

An opening 41 is provided in the cover 21 of housing 13 (Figs. 1, 2, 3). As shown in Fig. 2, this opening 41 is arranged to permit access to adjusting member 33 when the control bar 35 is actuated by the turning of the key 25 in lock mechanism 24 into engagement with common trip bar 19. Adjustment can only be accomplished when the variable loading mechanism is engaged with the common trip bar 19.

The operation of the invention to vary the predeter mined overload setting of a circuit breaker is as follows: An authorized person in possession of a key 25 inserts it into lock 51 and turns clockwise. This results in the turning of lock mechanism 24 and the structure secured to it. With the circuit breaker in the On circuit position and the common trip bar 19 in its uppermost position under the influence of return spring 52, the continued clockwise turning of key 25 in lock 51 will bring notch 37 of control bar 35 into engagement with trip bar 19 as shown in Fig. 2. Full engagement of these elements will be indicated by an angular position of the key 25 of approximately to the initial position. With the mechanism in this position a screwdriver may be inserted into opening 41 to either advance or retard adjustable member 33 relative to control bar 35. The influence of calibrating spring 40 which resists downward movement of control bar 35 about pivot 30 is thus increased or de- I 3 creased. The nature of this adjustment is determined by the overload setting desired.

With the mechanism in the engaged position of Fig. 2, the occurrence of an electric current in excess of that desired in one or more of the load circuits connected to the circuit breaker will cause one or more of the magnetic trip'coil units 16 to be energized. The corresponding armature or armatures 17 will be attracted downwardly to such energized magnetic trip coil'units 16. Through triu bar actuator 18, the common trip bar 19'will' also be drawn downwardly against the restraining force of return spring 52 and calibrating spring 40, the latter acting through control bar 35 and adjusting member 33. Until an overload current of sufiicient magnitude acting through the structure above described can overcome the force of return spring 52 and calibrating spring 40, the circuit breaker mechanism remains in the on or closed circuit position.

, When such occurs, the common trip bar 19 moves downit ceases to flow through the magnetic trip coil units 16.

These coils then become de-energized and release their respective armatures 17, thereby permitting common trip bar 19' and control bar 35 to move upwardly under the force of springs 52 and 4%), respectively, to the position shown in Fig. 2. The trip mechanism is then ready to operate it a fault should again occur in any of the load circuits. If it is no longer desired to vary the overload setting, the key can be reinserted in lock 51 and the control bar rotated counterclockwise out of engagement with common trip bar 19 to the position of Fig. l. The breaker will then operate according to the predetermined setting.

Another embodiment of the invention is shown in Fig. 4. This embodiment utilizes the same lock described above. A cam member 61 of the shape shown in Fig. 4 is secured by fasteners 27 to lock mechanism 24. A support member 62 is pivotally secured by pivot pin 70 to a bracket 63 attached to the underside of cover 21 of housing 13. Pivotally secured to support member 62 by a pivot pin 65 is a control bar 64. A calibrating spring 67 is anchored by one end at an intermediate point on support member 62 and by the other end to a sliding mounting 66 on control bar 64. The sliding mounting 65 may be held inposition on control bar 64 by any appropriate locking means as, for example, a set screw. An operating spring 68 has one end secured ad acent to the lower end of support member 62 and. the other end secured to'a bracket 69which pivots freely relative to cam member 61. Operating spring 68 constantly biases support member62 clockwise about pivot 70.

The desired overload setting. in this particular form of the invention is obtained by disengaging the mechanism as described below from common trip bar 19 and then removing cover 21. Sliding mounting 66 can then be moved along control bar 64until the tension-in calibrating spring 67 corresponding to the overload setting desired isobtained.

This embodiment operates in the following manner: With the mechanism in the disengaged-position, as shown by dotted lines in Fig. 4, and it is desired to vary the predetermined setting of the circuitbreaker, the key 25 is turned in lock 51. Lock mechanism 24 turns as the key isturned, carrying withit cam member 61. Support member 62 is held against cam member 61 by operating spring 68 so that it will respond laterally to the cam formation. Further rotary movement of cam 61 permits support. member 62 to move inward carrying with it control bar 64. After a 90 angular turn of key 25, the position drawn in solid lines in Fig. 4 is obtained. The lower end of control bar 64 moves into a position beneath common trip bar 19'. An overload of sufiicient degree will then pull common trip bar 19 down against the force of return spring 52 and calibrating spring 67. The further functioning of the mechanism is as described above.

The variable trip mechanism is disengaged from common trip bar 19 by rotating key 25 counterclockwise. Support member 62 is biased against the force of spring 68 by cam 61 to the dotted line position of Fig. 4 thereby removing control bar 64-from its position beneath common trip bar 19.

Now having described our invention, reference should be had to the claims which follow for the scope thereof.

We claim:

l. In a circuit breaker having a control mechanism, a trip bar adjacent said control mechanism for initiating operation thereof to move the circuit breaker to the open circuit position, electroresponsive means including an armature operatively positioned to actuate said trip bar upon occurrence of an overload in the electrical. circuit containing said circuit breaker, a variable'lo'ading mechanism selectively engageable with said trip bar for altering the predetermined overload setting of said circuit breaker.

2. In a circuit breaker having a control mechanism, a trip bar adjacent said control mechanism for initiating operation thereof to move the circuit breaker to the open circuit position, electroresponsive means including an armature operatively positioned to actuate said trip bar upon occurrence of an overload current in the electric circuit containing said circuit breaker, a variable loading mechanism selectively engageable with said trip bar for altering the predetermined tripping characteristics of said circuit breaker, said variable loading mechanism including a lock adapted to be actuated by a key and thereby move said variable loading mechanism into, and out of, engagement with said trip bar and to prevent unauthorized positioning of said variable loading mechanism with respect to said trip bar.

3. In a circuit breaker having a control mechanism, a trip bar adjacent said control mechanism for initiating operation thereof to move the circuit breaker to the open circuit position, electroresponsive means including an armature operatively positioned to actuate said trip bar upon occurrence of an overload in the electrical circuit containing said circuit breaker, a variable loading mechanism selectively engageable with said trip bar, said variable loading. mechanism including a mounting member, a control member secured to said mounting member to permit movement relative to said mounting member, and means between said mounting member and said control member for altering the predetermined overload setting of said circuit breaker.

4. In a circuit breaker having a control mechanism, a trip bar adjacent said control mechanism for initiating operation thereof to move the circuit breaker to the open circuit position, electroresponsive means adjacent said trip bar to actuate said trip bar upon occurrence of an overload in the electrical circuit containing said circuit breaker,'a variable loading mechanism selectively engageable with said trip bar, said variable loading mechanism including a lock, a mounting member secured to the rotatable portion of said lock to turn therewith when said portion is actuated by the turning of a key in said lock, a control member secured to said mounting member to permit movement relative to said mounting member, and means between said mounting member and said control member for altering the predetermined overload setting of said circuit breaker.

5. In a circuit breaker having a control mechanism, a trip bar adjacent said control mechanism for initiating operation thereof to move the circuit breaker to the open circuit position, electroresponsive means including an armature operatively positioned to actuate said trip bar upon occurrence of an overload electric current in the electrical circuit containing said circuit breaker, a variable loading mechanism selectively engageable with said trip bar, said variable loading mechanism including an actuating member, a support member adapted to be engaged by said actuating member, a control member secured to said support member to move relative thereto, and means between said support member and said control member for altering the predetermined overload setting of said circuit breaker.

6. In a circuit breaker having a control mechanism, a trip bar adjacent said control mechanism for initiating operation thereof to move the circuit breaker to the open circuit position, electroresponsive means adjacent said trip bar to actuate said trip bar upon occurrence of an overload electric current in the electrical circuit containing said circuit breaker, a variable loading mechanism selectively engageable with said trip bar, said variable loading mechanism including a lock, an actuating member secured to the rotatable portion of said lock to turn therewith when said portion is actuated by the turning of a key in said look, a support member adapted to be engaged by said actuating member, a control member secured to said support member to move relative thereto, and means between said support member and said control member for altering the predetermined overload setting of said circuit breaker.

7. A variable loading mechanism adapted to be selectively engageable with a circuit breaker control mechanism including a lock having fixed and operable portions, a mounting member secured to the operable portion of said lock, 21 control member secured to said mounting member to move relative thereto, and variable means between said mounting member and said control member for increasing the predetermined overload setting of a circuit breaker when said variable loading mechanism and said circuit breaker control mechanism are in engagement.

8. A variable loading mechanism adapted to be selectively engageable with a circuit breaker control mechanism including a lock having fixed and operating portions, an actuating member secured to the operating portion of said lock, a support member, a control member secured to said support member for movement relative thereto, and means between said support member and said control member for increasing the predetermined overload setting of a circuit breaker when said variable loading mechanism and said circuit breaker control mechanism are in engagement.

9. In a circuit breaker having a control mechanism, a manual operator for actuating said control mechanism, a trip bar adjacent said control mechanism for automatically initiating operation thereof to move the circuit breaker to the open circuit position independent of the position of said manual operator, electroresponsive means including an armature operatively positioned to actuate said tn'p bar upon occurrence of an overload in the electrical circuit containing said circuit breaker, a variable loading mechanism moveable from a retracted position to engage said trip bar to thereby increase the overload setting of said circuit breaker, and moveable from engagement with said trip bar to restore the predetermined overload setting of said circuit breaker.

10. In a circuit breaker being comprised of a combination of a pair of cooperating contacts, a control mechanism, an electroresponsive automatic trip mechanism, a means; said control mechanism being operatively connected to said pair of cooperating contacts; said automatic trip mechanism being operatively connected to said control mechanism to automatically disengage said cooperating contacts upon a predetermined overload condition; said means including a control bar; said control bar being selectively engageable with, and disengageable from, said automatic trip mechanism to increase the predetermined overload rating of said circuit breaker when so engaged.

11. In a circuit breaker being comprised of a combination of a pair of cooperating contacts, a control mechanism, an electroresponsive automatic trip mechanism, a means; said control mechanism being operatively connected to said pair of cooperating contacts; said antomatic trip mechanism being operatively connected to said control mechanism to automatically disengage said cooperating contacts upon a predetermined overload condition; said means being pivotally secured to said circuit breaker about a stationary pivot; said means including a control bar; said control bar being selectively engageable with, and disengageable from, said automatic trip mechanism to increase the predetermined overload rating of said circuit breaker when so engaged.

12. In a circuit breaker being comprised of a combination of a pair of cooperating contacts, a control mechanism, an electroresponsive automatic trip mechanism, a variable means; said control mechanism being operatively connected to said pair of cooperating contacts;

said automatic trip mechanism being operatively connected to said control mechanism to automatically disengage said cooperating contacts upon a predetermined overload condition; said means being pivotally secured to said circuit breaker about a stationary pivot; said variable means comprising a control bar and a variable biasing means, operatively connected thereto; said control bar being selectively engageable With, and disengageable from, said automatic trip mechanism to increase the predetermined overload rating of said circuit breaker when so engaged.

13. In a circuit breaker being comprised of a combination of a pair of cooperating contacts, a control mechanism, an electroresponsive automatic trip mechanism a variable means; said control mechanism being operatively connected to said pair of cooperating contacts; said automatic trip mechanism being operatively connected to said control mechanism to automatically disengage said cooperating contacts upon a predetermined overload condition; said means being pivotally secured to said circuit breaker; said variable means comprising a control bar, a support member, an actuating member, a variable biasing means; one end of said control bar being pivotally mounted to said support member; said variable biasing means being operatively connected to said control bar and said support member; said support member and said actuating member being operatively conected to move in unison; said control bar being selectively engageable with, and disengageable from, said automatic trip mechanism to increase the predetermined overload rating of said circuit breaker when so engaged.

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